Is excess protein converted and stored as body fat?

I am not a nutritionist, but I have been a personal trainer for over 10 years, have a Master of Science degree and have taken several nutrition classes and seminars/conferences on nutrition. I have always understood that any excess calories are stored as fat. Recently, I got into a discussion with a new gym member who has had success with weight loss through a high protein diet--he insists that the body utilizes all protein, no matter if it exceeds calorie output. I have been researching protein specifically, if it actually is converted/stored as fat, and have not found any solid research results. Are there any Registered Dieticians or Nutritionists who can answer this question?

Answers (4)

here is a reference from the ACE website. The answer was given by Cedric Bryant.

"The human body is unable to store extra protein. Protein consumed in excess of the body's needs is not used to build muscle; rather, it is used for non-protein bodily functions.
If individuals consume protein in excess of their caloric and protein needs, the extra protein will not be stored as protein. Unfortunately such extra protein is converted to and stored as fat. As a result, if individuals consume large amounts of extra protein in addition to their regular dietary intake, any weight gain would very likely be in the form of fat.
Another important point to keep in mind is that the potential for harm exists if protein is consumed in excess. Such harm is most likely to occur in the individual who consumes protein or amino acid supplements.
For example, excess protein may lead to dehydration, because protein metabolism requires extra water for utilization and excretion (i.e., elimination) of its by-products. Since exercising individuals are already at an increased risk for dehydration, the additional strain of protein waste excretion may further promote dehydration.
Excess protein has also been shown to lead to an increase in the loss of urinary calcium. A chronic calcium loss, due to excess protein intake, is of particular concern because it may increase the risk of osteoporosis, especially in women.
Source: Bryant, Cedric X. 101 Frequently Asked Questions about "Health & Fitness" and "Nutrition & Weight Control". Sagamore Publishing, 1999."

I'm not a RD or Nutritionist. I do have a BS degree in Exercise Science, am also a certified personal trainer with ACSM, and fitness nutrition specialist with ISSA.

Short answer yes, but most lay people don't really understand what or why they are following this technique. Most of the people they see doing it look fit, so they think it must be good for them too.

2 Things:

1) One reason people eat more protein than the average person requires is because their diet is so low carb that they have to make up for the caloric deficit with another macronutrient (i.e. protein & fat). However, the rule is to not be on a prolonged high protein diet for an extended period of time, and it should be timed to one's specific goal. Example: This is why some athletes "cycle" with periods of high protein as well as periods of high carb during certain times of the year to prepare for a sport/competition. They know that eating this way for extended periods is unsafe/counterproductive.

2) Another reason people eat high amounts of protein is to stimulate the thermic effect of feeding, and reduce water weight. Although the extra calories needed to metabolize protein is negligible, some folks feel like they'll take that extra boost just the same. We also know that a carbohydrate carries more water than a protein, so that's an automatic loss in body weight there. Example A: One reason folks are so successful on Atkins or other low carb diets is because less carbs in the diet will cause an automatic drop in water weight.

Example B: Many marathoners/endurance athletes like to "load" before an event to get that extra water (i.e. hydrate the body) and gain some extra sugar storage at the muscular level to aid performance.

The body will utilize all protein intake, but not necessarily to build muscle or other "typical" vital functions requiring protein; and like any other macro-nutrient any excess calories from protein are stored as body fat.

If I create 3 study groups, put one on an Atkins-based diet, the second on an Ornish (the "anti-Atkins" low fat, little meat) and a third on something more balanced in between, and they all successfully follow their diet for a period of time, they will lose the same amount of weight regardless of which diet they are on so long as the total amount of calories would be the same. It's simply a matter of calories in, calories out.

BUT what will happen is that I would have more dropouts from both the Atkins and Ornish group than I will from the Balanced group. Furthermore, even if the weight loss is the same from each group, if I do a follow up study in an additional 6 months, I would find that the Balanced group maintained more of their weight loss because it wasn't as restricting as the other diets; whereas the other groups would more likely revert to old, less healthy eating choices.

I let my clients know the key is to integrate balance and moderation of all foods, rather than restriction and elimination of some and over-excess of others.

Unfortunately this myth is continuing to spread throughout society. The path for excess Amino Acids to be converted into fatty acids does exist, however this is only done in the most extreme cases. There was a study done recently throughout the last few years that dispels the "excess protein gets converted into fat myth". The study was done by George A. Bray, an MD of the Pennington Biomedical Research Center over in Baton Rouge. Here is the link for the study>http://newsatjama.jama.com/2012/01/03/fat-accumulation-dictated-by-excess-calories-not-protein-content/

Also high protein intake is not a sole contributor to loss of bone mass. In the early years it was thought that since protein is acidic, then high levels would contribute to an imbalance in the Body's PH levels and in order to correct the imbalance, the body would then use calcium stores from it's bones. This however is false and higher protein intake actually contributes to increases bone density as this was discovered by Jane E. Kerstetter, a researcher at the University of Connecticut. She discovered that this increase actually helped increase the rate of calcium absorption and she also concluded: “The recommendation to intentionally restrict dietary protein to improve bone health is unwarranted, and potentially even dangerous to those individuals who consume inadequate protein." (Jane Kerstetter).

Higher energy expenditures of the evolved Primate brains of our species has increased the need four our species to consume high energy food sources such as protein in order to support this evolutionary trait. Considering this, one would be able to infer that nature would not build an advantage for the species and that advantage also be its weakness. If so, our species would have died out long ago as it would have been more difficult to evade predators with higher protein needs weakening our skeletons. Remember this if nothing else: "Nature always takes the path of least resistance"